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Aviation History
1957
1957 - 1357.PDF
13 September 1957 447 valve, designed primarily for controllingthe weapon's control fins. The valve amplifies a small signal from the guidancesystem and converts it into a powerful hydraulic signal to the control actuators.The push-pull input signal may vary be- tween 0 and 10 mA, and the output is 9cu in/sec with a 2,000 lb/sq in pressure drop. The system pressure may be as highas 4,000 lb/sq in and the frequency response exceeds 100 cyc/sec. The wholevalve weighs 1.88 lb. A related unit, per- forming a similar function but with agreater output, is a two-stage servo valve weighing 4.43 lb. With other characteris-tics similar to those of the single-stage assembly, the output is up to a maximumof 45 cu in/sec. Most of the guided-weapon accessoriesby Dunlop's Aviation Division are com- ponents for use in pneumatic systems. Atypical example of their techniques was provided by an air bottle, in the top ofwhich is mounted a pressure-reducing valve while the body of the latter containsa miniature solenoid-operated control valve. Naturally, as the bottle dischargesits pressure falls, and the reducing valve has to maintain constant supply at a con-stant pressure, even when the bottle pres- sure has fallen almost exactly to the samelevel. The solenoid-operated valve operates ata nominal 24 V.D.C., and requires a 0.25- sec impulse to initiate operation. Afterdischarge of the bottle the valve reseats, so that the bottle need only be recharged foruse a second time. Two solenoid valves are mounted in a twin starter valve manu-factured for de Havilland Propellers, and clearly used to trigger off two distinct airsupplies in Firestreak. Machined from a single metal block, the body measuresabout 5 in by 2in by lin and also incor- porates a pair of reducing valves. Elliott Brothers Few companies any-where in the world are conducting so many missile firings for pure research, sinceElliott are sub-contractors to the M.o.S. for virtually all the electronics in the much-used GPV, and have their own team at Aberporth. An outdoor exhibit showed a sectionedGPV (see Short and Harland) complete with its horning head. The "target" was aconical aerial emitting radar pulses of the type reflected by a target to give semi-active homing. A bent spinner in the centre of the missile "dish" rotated to giveconical scanning, the pulses being modu- lated and the target direction being denotedby the phase of the resulting received signal. This signal was fed back to anamplifier and used to drive gyros which, in turn, pointed the parabolic scannerdish at the target. This set up an error signal which, upon being amplified, wassuitable for feeding back to the main steer- ing gear of the vehicle. Target range was obtained by bladeaerials on the sides of the fore-body, which picked up pulses from a second groundradar (synchronized with the pulses from the "lamp" set illuminating the target, butof different frequency). The time-differ- ence between reception of the two sets ofpulses was used to "gate" the missile radar, and prevent the latter from responding toany signals except those emanating from the individual target selected. A series ofphotographs showed a GPV actually strik- ing a metal-sphere target suspended be-neath a balloon. Elliott are also, of course, a major manu-facturer of digital and analogue computers, and use both types of equipment in analy-sis of missile behaviour at Aberporth and Woomera. Data analysis is carried out atthe company laboratory at Boreham Wood, Herts, and test programmes are also inhand for all the principal members of the British G.W. industry. English Electric This industrial giantis one of the few firms—if not the only firm —in the world capable of developing andmaking a complete advanced weapon sys- tem without outside help. Thunderbird,their rocket-propelled anti-aircraft weapon, is in bulk production for the Army, and onSeptember 3 an order was also placed by the R.A.F. It is an extremely good, compact, ruggedand effective missile, and apparently makes up in altitude what it loses to ramjet wea-pons in range. First seen at the S.B.A.C. show, it is a semi-active homing weapon,with cruciform wings and rear controls. English Electric stated last week that: "Thunderbird is one of a family of wea-pon systems being developed by English Electric and several hundred missiles havebeen fired at Aberporth (South Wales) and Woomera (Australia). The system em-braces ground radars, launchers, fire con- trol units and associated test equipment aswell as the actual missile. The missile has been engineered for progressive de-velopment and, as a result, it can be modi- fied to meet the ever advancing nature ofthe air threat by substituting new and im- proved main sub-assemblies without theneed to re-design the entire missile." Various examples of small G.W. testinstruments were exhibited by Graseby, including equipment for producing signalssuitable for telemetering. For the trans- mission of angle of incidence, the TypeGW.4 unit is used, with twin delta yaw- sensitive vanes governing twin potentio-meters. Typical angular ranges are ±5 deg and +12 deg. Another pair of exhibitswas concerned in the telemetering of ac- celeration: the GW.6 control transducer,capable of loading up to ±60 g, and the GW.5 and 8 acceleration recorders withlimits of ±2.5 g and ±100 g. Described as fully as security allows inour issue of August 16, Fairey Aviation's Fireflash was much in evidence at Farn-borough. Photographs showed that it is stored in two groups: Group I, compris-ing all explosive portions (warhead, fuse and boost motors) and Group II, compris-ing guidance gear, wings and controls. Rounds are delivered in shockproof andclimate-sealed containers and assembled, tested and checked as Groups I and II, after which the sections are put togetheron the loading trolley and wheeled out to the aircraft. Fairey are also European agents for theAustralian Department of Aircraft Produc- tion who manufacture the Jindivik radio-controlled target. Much used on the Woomera range, and shot at by both Fire-flash and Firestreak, Jindivik has been ex- ported to Sweden and is a very fine vehicle.An example was statically exhibited. Hairlok manufacture transport andstorage containers for the Firestreak. Ex- hibited was a version produced for theRoyal Navy, incorporating a hermetically sealed envelope and cushioning to resistfree-fall up to 24in with accelerations up to 25 g. One of the chief exponents of the artof powered flying controls, and referred to in that section, H. M. Hobson are alsobusily engaged in missile controls. They were the sub-contractors for this part ofthe Short/M.o.S. GPV test vehicle, and evolved for this application a basic servowhich is now also used in certain other vehicles, including the moving-wing CTVs(see paragraph on the M.o.S.). An out- door working system demonstrated thecharacteristics of the system, data for which are: stall torque, 1,750 lb-in at 2,000 lb/sqin; load inertia, 60 lb-in ; design operat- ing pressure, 2,000 to 3,000 lb/sq in;maximum response speed, 750 to 900 deg/sec; hydraulic horse-power, 3. Typical of the small Hymatic valves suit-able for guided-weapon applications is the starter valve, Type SV 17. This is a valvewhich, after retaining a pressure up to 4,000 lb/sq in for an indefinite period,opens the pressure for a one-shot opera- tion. It comprises a metal-foil diaphragmto seal the fluid line completely and a Bakelite tube containing gunpowder andan electric fuse. When the latter is ener- gized the charge ruptures the disc andallows the store of pressure to discharge at up to 31 lb/min with a pressure drop ofnot over 180 lb/sq in. Typical uses include fuel-dumping and starting. A valve typical of a different species isthe solenoid valve MD 23, in which a main valve is operated by system pressure re-leased by a pilot valve actuated by a D.C. solenoid. Weighing 1.5 lb it can controlmissile supplies at up to 4,000 lb/sq in, and passes a flow of up to 72.5 lb/minwith a pressure drop (at 50 cu ft/min from A system diagram of the British Messier servo-control, described on page 445. QUICK RELEASE BO0Y ACTUATOR RING ^COUPLING AIR BLEED MAIN OIL EXHAUST i'TRANSDUCER OIL TO TANK FOR GROUND TEST
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